Pumping pillar technology of fully mechanized caving face passing through abandoned roadway

Existing working face passing through abandoned roadway based on traditional support methods cannot adapt to changeable geological conditions well. Based on research background of 8103 fully mechanized caving face of Yongdingzhuang Coal Industry Co., Ltd. of Datong Coal Mine Group, basic roof deformation characteristics of the fully mechanized caving face passing through abandoned roadway were analyzed theoretically, and pumping pillar technology of fully mechanized caving face passing through abandoned roadway was put forward. The numerical simulation results show that with distance decreasing between working face and abandoned roadway, vertical stress of surrounding rock in abandoned roadway supported by pumping pillar changes from "double peak" to "single peak" and then "double peak", and convergence of surrounding rock increases firstly and then tends to be stable, which indicate that the pumping pillar can withstand advancing abutment stress of the face and ensure safety of the face passing through abandoned roadway. The technology has been successfully applied in field with good stability of surrounding rock. The maximum convergence between roof and floor is 282 mm, and that between two side walls is 152 mm.